Hepatoprotective properties and biotransformation of berberine and berberrubine by cell suspension cultures of Dodonaea viscosa and Ocimum basilicum

• Berberrubine was semisynthesised from berberine isolated from Berberis vulgaris.
• Berberine and berberrubine were biotransformed by O. basilicum and D. viscosa.
• Berberrubine was methylated by O. basilicum and oxidized by D. viscosa.
• Berberine was biotransformed into palmatine by Dodonaea viscosa cultures.
• Berberrubine showed best hepatoprotective results by decreasing the TBARS level.

IntroductionBiotransformations are having great potential to generate novel or known products more efficiently. Berberine (BB) represents one of the most studied among the naturally occurring protoberberine alkaloids due to its wide range of pharmacological activities.ObjectiveFirstly, to isolate BB from Berberis vulgaris roots, semisynthesis of berberrubine (M1). Secondly, to investigate the liability of BB and M1 for biotransformation by cell cultures of Ocimum basilicum and Dodonaea viscosa focusing on the production of more potent hepatoprotective metabolites. Finally, the hepatoprotective properties of both BB and M1 are studied against B. vulgaris alcoholic extract.MethodsFor the biotransformation, BB and M1 (10 mg/mL) in methanol, equal volume of methanol (control) and distilled water (blank) were added to Suspension cultures of O. basilicum and D. viscosa and were kept under light at 23 °C on a gyratory shaker at 100 rpm for 14 days before the cells being harvested and the contents of each flask, lyophilized separately were dissolved in methanol and subjected to TLC and LC/MS analyses. For hepatoprotective properties TBARS was determined in liver homogenate, protein free supernatant according to the method described by Tappel and Zalkin (1959). The TBARS level was calculated against control according to the following equation:TBARSlevelnmol/mL=Absorbance/0.156.ResultsBB was identified in the root extract using HPLC. LC/MS analyses of lyophilized media from all cultures showed the absence of biotransformation. However, M1 was biotransformed by O. basilicum and D. viscosa cultures into BB (100%) and a new oxidized derivative of M1 (M1TD; 78.9%), respectively, while BB was transformed into palmatine (27.7%) by culture of D. viscosa only. For the hepatoprotective potential of M1and BB in comparison with B. vulgaris extract, all samples decreased Thiobarbituric acid reactive species (TBARS) level in a dose dependent manner. IC50 of BB, B. vulgaris ethanolic extract and M1 were 19.5, 16 and 9.8 μg/mL, respectively. M1 with IC50 9.8 μg/mL was the most potent inhibitor of lipid peroxidation induced by Fe2+ and H2O2 in liver homogenate at P < 0.05.ConclusionThis study reports that the biocatalysis system of D. viscosa cultures showed appreciable capacity in oxidizing the phenolic group of M1 at C-9 and opening of the methylenedioxy ring of BB at non-extreme pH or temperature, followed by methylation to give palmatine. However, the biocatalysis system of O. basilicum culture showed a great capacity towards methylation of phenolic groups as evidenced by methylating OH of M1 at C-9 to give BB. In vitro biological tests indicated that M1 possess better hepatoprotective properties than BB and B. vulgaris methanolic extract.